Press for vulcanizing play balls and similar articles



30, 1 942. V w. HUMPHREY PRESS FOR VULCANIZING PLAY BALLS AND SIMILARARTICLES Filed April 15, 1939 Sheets-Sheet l INVENTOR l/uryH/Rty Wm 15?E.

ATTORNEYS June 1942- w. E. HUMPHREY 88,356

PRESS FOR VULCANIZING PLAY EALLS AND SIMILAR ARTICLES Filed April 15,1939 3 Sheets-Sheet 2 Iv vENTOR .54 M11. rm 5. HUMP/4R5) PRESS FORVULCANIZING PLAY BALLS AND SIMILAR ARTICLES Filed Apri'l lS, 1939 3Sheets-Sheet 3 lllllllllllulr ATTORNEYS Patenteil June 30, 1942 PRESSFOR VULCANIZING PLAY BALLS AND SIMILAR ARTICLES Walter E. Humphrey,Jeannette, Pa.

Application April 15, 1939, Serial No. 268,000

6 Claims. (Oi. 18-17) The present invention relates to presses for usein vulcanizing, hollow objects wherein the objects are filled with gasor fluid under pressure and vulcanized in that condition. While thepress is intended for the manufacture of'holl'ow rubber play balls, suchas may be used as centers for tennis balls, the principles of theinvention may be more widely extended and used in similar or analogousfields. The description and drawings show a press of the type hereincovered which is especially adapted for the particular purposespecified; but it will be appreciated that the showing is by way ofillustrating the best known or preferred form of the invention andchanges and modifications may be incorporated in other embodimentswithout departing from the essential elements of the invention.

The press shown herein is particularly adapted for carrying out theprocess for curing play balls shown in my copending application, SerialNo.

243,929, filed December 5, 1938. Briefly stated this process consists informing two hemispherical play ball sections which may be partiallycured if desired, it being advantageous to semi-cure the sections in anordinary platen press to conserve the time required in the pressillustrated herein. These sections are placed in oppositely facingcavities in opposed mold plates, which are then brought together topartially and approximately closed position, a narrow space interveningbetween the opposed edges of the ball sections. The space about the ballsections and between the faces of the mold plates is then closed oil orsealed by a fluid tight barrier and the fluid under pressure, generallyair, is admitted to the space between the mold plates and flows into theopen cup-like ball sections. While the barrier is maintained, themoldsections are brought together under heavy pressure, so that theedges of the ball sections are forced into intimate contact and whichjoin or fuse together under the pressure and heat of vulcanization.

The press of this invention is preferably made in dual or double formwith superposed pairs of mold sections to permit the use of a battery ofIn the drawings:

Fig. l is a front elevation of the press in fully open position,portions thereof being in section orraroken away better to showtheoperatin P Fig. 2 is a side view of the press in the same condition;

Fig. 3 is a front elevation with the mold plates brought together intheir partially closed position, that is, the position which the partsoccupy while the pressure is being admitted to the hollow ball sections;

Fig. 4 is a view, somewhat enlarged, of the upper portion of the presswith the mold sections brought together for the'vulcanizing operation;

Fig. 5 is an enlarged detail of the mold sections in open position asin- Figs. 1 and 2;

Fig. 6 is a view of the parts in the position of Fig. 3;.

' Fig. 7 as in the position of Fig. 4; and

Fig. 8 is an enlarged view of the completed hollow bail.

Referring first to the details of the process and particularly to thesteps which are covered in the copending application referred to above,the

press-is adapted and intended, in the form shown,

to operate upon two sets or banks of molds so that two sets of balls arecured in a single operation.

The upper pair of molds is indicated by the numerals l and 2representing top and bottom mold elements. and the lower pair of moldsby the numerals} and 4. In these mold sections are provided thehemispherical cavities i, facing each other in which the uncured orpartially cured rubber ball sections i-are placed, the arrangement beingsuch that each rubber section will project to a limited extent beyondthe face of its mold section, so that as the mold faces are broughttogether the edges of the rubber segments of each ball will be broughtinto firm engagement and the rubber thus forced together molds, so thatthe operations may be more eco- ;closures contained herein, which willbe understood to represent the best known or preferred form of theinvention.

so that a tight seam or splice is made about the completed ball.

In-the :iorm shown. the upper mold section I is attached to a heated orsteam platen l which is carried upon the underside of the stationarypress head ll. The lower section I is attached to the heated platen I!which is carried in the upper side of a movable press head II, which isslidably mounted on the main supporting pillars l5 which extend from thestationary press head ill to the supporting base It. The mold sections 2and l are attached to heated platens H and It, carried by the top andbottom sides of an intermediate or floating plate 20 which is alsoguided for movement upon the pillars l6. When the press is fully opened,as shown in Figs. 1 and 2, the plate 20 is supported in its intermediateposition by pairs of rods 2| to which it is secured. These rods'areextended to pass through webs 22 on the upper press head l and webs 23on the movable press head l4. On the upper ends of the rods are the locknuts 24 by which the location of the floating plate 20 is fixed when thepress is open. On the lower ends of the rods are located the lock nuts26 which serve to draw down the floating plate 20 as the press isopened.

In the base l6 of the press is located the cylinder 30 in which ismounted the hydraulic ram 32 upon which is carried the movable presshead l4. This ram is supported in its lowermost position by lugs 33 onthe base of cylinder 30. At the sides of the base are located twosmaller cylinders 34 which are intended to operate as draw-backcylinders, the rams within these cylinders being connected by tie rods36 to the movable press head.

0n the top or stationary press head is located a high pressure cylinder36 in which is a ram 31, depending from which is the central rod or post38 slidably mounted in the upper press head. At about the point wherethe rod 38 projects from the press head it is reduced and provided witha threaded area 39, and below this point it is further reduced as at 40.At its lower end the rod is screw-threaded and on this portion isadjustably mounted a collar 42 held in adjusted position by the lock nut44. On the threaded area 33 is adjustably mounted a sleeve 46 held inposition by the lock nut 41. The sleeve is reduced as at 46 and thenextended to pass through an opening in the floating plate 20. As shownin Figs. 3 and 4, the adjustable collar 42 is arranged to be received ina depression in the movable press head and to contact the surfacethereof at the point 48 when the lower press head is brought to theposition in which the mold sections are substantially-closed and whenthe ball segments are to receive the fluid pressure. Similarly, theshoulder 46 contacts the upper face of the floating plate 20.

The distance from the under face of the upper press head in the shoulder46 is approximately M; of an inch greater than the combined thickness ofthe molds l and 2 and their steam platens. Likewise, the distance fromthe shoulder 46 to the lower surface of the collar 42 is approximately Vof an inch greater than the combined thickness of the floating plate 20and the mold sections 3 and 4 and their steam platens. The dimension ofV; of an inch is given as illustrative only and may be adjusted ineither case by the adjustments of the sleeve 46 on the rod 36 and theadjustment of the collar 42 on the reduced end of the rod 36. It issuflicient in each case to provide the passage between the opposingfaces of the pairs of mold plates to the interior of the ball, allowingfor the projection of the ball segments beyond the faces of the moldplates and permitting the unobstructed passage of the fluid pressureintothe ball segments. The purpose will be further understood from anexamination of Fig. 3 in which the mold sections are shown in theirspaced relation ready for the admission of the fluid pressure to theinterior of the ball segments, for in that view no movement of the rod38 has taken place, but the shoulder 46 is in contact with the floatingplate 24 and the collar 48 is in contact with the upper face of the ramor movable press head.

For the successful operation of the press, it is essential that the twopairs of mold plates be each spaced apart when the press is in thecondition shown in Fig. 3 and unless means were provided to lift thefloating plate as the ram reached the position of Fig. 3, the lower pairof mold plates would close together, while the upper mold plates wouldbe separated twice the alloted amount, or with the figure 01' A; of aninch as given, the pair of lower mold plates would be in contact, whilethe upper pair were spaced ,4; of

carried in the lower or movable press head and project sumciently aboveitssurface to contabt with and be compressed by the intermediate orfloating plate as the press reaches the intermediate position. Thesprings are sumciently strong to lift the intermediate plate until it isarrested by contact with the shoulder 46.

The upper or high pressure ram 31 is under a constant given pressure ofa very substantial degree, approximately 1000 lbs. per square inch beingemployed in operative press structure. The lower ram 32, however, isarranged to have two pressures exerted upon it, a high pressure and alow pressure. These pressures are admitted through the line 62 and thethree-way-valve 63, the high pressure line being indicated, for example,at 64 and the low pressure heat 66; 66 is intended to represent theexhaust. The low pressure may tor example, be approximately 300 lbs. persquare inch and the high pressure 1000 lbs. per square inch, it beingobserved that the ram 32 is greater in area" than the ram 31 so that itstotal eflective pressure is suflicient to overcome the pressure on theconstant pressure ram 31.

It will be understood that the press may be inverted or even may be in ahorizontal position without changing the principles of the invention.

Referring now to the details of the mold plates which have been brieflydescribed. Each pair of mold plates has one plate with a sealing memberthereon adapted to seal the space between the mold plates when they arebrought into the intermediate position so that pressure will be retainedin the space communicating with the ball segments. As shown, each topplate is provided with a downwardly facing channel 61 in which isinserted a flexible U-shaped gasket or packing ring 68 which is movabletherein. This packing ring should be made of asbestos composition,asbestos, or some other heat resisting material so that it willwithstand the heat of the steam platens required to vulcanize the balls.This gasket and its receiving channel extends completely around theplate and encloses all 01' the ball cavities 6 and is adapted to contacta complementary sealing ring 69 in the opposing plate. A source oi fluidpressure indicated by the pipe 60 is let into the channel at one or morepoints by which pressure is applied to project the gasket into sealingrelation with the ring 63 when the plates are in the intermediate orpartially closed position shown in Fig. 6.

Into the space between the mold plates and within the gasket is also leta pipe line 62 with one or more outlets to the space between the moldplates so that when the parts are in the position shown in Fig. 6, fluidunder pressure, admitted to the space through the pipe 62, will flowinto the cup-shaped ball segments through the space between their edges.

After the admission of the required fluid pressure the press iscompletely closed for the vulcanizing operation. This is accomplished byadmitting the high pressure to the ram 32, which due to its larger areaovercomes the constant pressure on the ram 31 and closes the mold platestogether against the stationary head plate. This operation compressesthe springs 50, closing the space between the lower pair of mold plates,raises the floating plate 20 and closes the upper pair of mold plates.This position is shown in Fig. 4. During the vulcanizing operation thepressure to the lines 60 and 62 may be shut off, although it isadvisable thatthese operations be not performed until the end of thevulcanizing operation and until vulcanization has progressedsufliciently to insure a permanent seam about the ball.

After the requisite vulcanizing period the high pressure on the ram 32is relieved and the lower ram will return to its original position, theintermediate plate being suspended on the lock nuts 24. In order toinsure that the parts return to their original position, pressure may beadmitted to the pull-back rams 34 which will overcome any tendency forthe plates to stick or bind on their slideways.

The cured balls with the edges of the segments vulcanized together maythen be removed.

It is obvious that the control valves for the various pressure lines, i.e., the low and high pressures to the ram 32, the pressure to thepull-back cylinders I4 and the pressure to the lines 60 and 62 whichseal and inflate the ball segments, may be controlled by any standardtiming mechanism, instead of being manually operated. The pressure onthe ram 31 is constant.

It should also be stated that before the ball segments are placed inposition, their edges should be buffed and cemented so that the bondbetween the segments will be closely knit and no leakage in the ballswill be observed. When the plates are opened the balls will expand to adegree determined by the thickness of the stock' and the pressureemployed. This expansion of the balls will facilitate their removal fromthe mold cavities. It should also be stated that the pressure on theline 60 to the sealing gasket should exceed somewhat the internalpressure for the balls admitted through the line 62 to prevent blowingout of the gasket.

It will be understood that while the invention has been described forthe manufacture of play balls, it is by no means confined to thatparticular article, but may be extended to other hollow pressure-filledarticles, toys or the like.

What is claimed is:

1. A press for vulcanizing hollow pressure filled articles comprising anintermediate mold plate and opposing mold plates on either side thereofand forming two pairs of cooperating mold plates, cavities in the moldplates, a movable barrier for each pair of plates and surrounding thecavities therein, means to project the barriers to form a fluid tightchamber between each pair of mold plates, means to introduce fluidpressure within the barriers, yielding means to hold the plates inspaced relation with the barriers in chamber forming position, and meansto overcome the yielding means and to force the mold plates intocontact.

2. A press of the type specified comprising two mold plates withopposing cavities, a constant pressure ram having means associatedtherewith to arrest the movement of one of the plates at a point wherethe mold faces are out of contact, in partially closed position, asecond ram opposed to the constant pressure ram acting upon the otherplate, means to supply fiuid under two different pressures selectivelyto the second-named ram, the pressure of the lower pressure fluid beinginsuflicient to overcome the pressure on the first-named ram whereby themovement of the second-named ram is arrested and the pressure of thehigher pressure fluid being suflicient to overcome the pressure actingon the first named ram and bring the mold faces in contact.

3. A press in accordance with claim 2 provided with means to introducefluid pressure between the mold faces when in partially closed position.

4. A press forvulcanizing hollow pressure filled rubber articlescomprising a stationary press head, a movable press head. a plateintermediate the press heads, means to suspend the intermediate platebetween the press heads in fully open position, but to permit it to movetoward the stationary press head, pairs of molds with opposing cavitieson the press heads and the intermediate plate, spring means between themovable press head and the intermediate plate, a constant pressure ramhaving associated therewith a stop for arresting the movement of theintermediate plate, a ram for the movable press head, means to supplyfluid under two different pressures selectively to the second named ram,the pressure of the lower pressure fluid being insufficient to overcomethe pressure on the firstnamed ram whereby the movement of thesecondnamed ram is arrested and the pressure of the higher pressurefluid being sufiicient to overcome the pressure acting on thefirst-named ram and bring the mold faces in contact.

5. A press in accordance with claim 4 having means to introduce fluidunder pressure between the mold faces when in partially closed relation.

6. A press in accordance with claim 4 having a yielding barriersurrounding the molds and means to introduce fluid pressure between themold faces and within the area surrounded by the barrier when the moldsare in partially closed relation.

WALTER E. HUMPHREY.

